This invention relates to vane apparatus for clog resistant pumps. Such pumps may roughly be categorized as centrifugal pumps and axial pumps.
The centrifugal pump comprises an impeller consisting of a hub, at least one cover disc on said hub and a number of vanes, a so-called open impeller. A closed impeller is provided with two cover discs and intermediate vanes. Common for the two types is that the liquid is sucked into the centre of the impeller in an axial direction and leaves it tangentially at the periphery.
The axial flow pump differs from the centrifugal pump in that the liquid leaves the pump in a substantially axial direction. This linking of the fluid is taken care of by a number of vanes in the pump housing after the impeller. These vanes also normally serve as supporting elements in the housing construction.
When pumping sewage water and certain types of process water containing elongated fibres, the pumping may be disturbed by rags, fibres, etc., getting stuck to the front edges of the vanes on the impeller and in the pump housing. Such build-ups can initially create vibrations in the pump, consequently the efficiency decreases and finally the pump might get totally clogged. One way to make the objects leave the vanes is to let the pump rotate backwards at certain intervals, but this is of course not an acceptable solution. Another way to diminish the clogging risk is to provide the pump with cutting means which divide the pollutions into pieces before they are sucked into the impeller. An example of such a solution is shown in the Swedish Pat No 820 5774-6 (U.S. Pat. No. 4,640,666). A disadvantage with this solution is that the cutting means may be quickly worn out which might cause the clogging problem to become even worse.
The purpose of this invention is to solve the clogging problems mentioned above in a totally new and different way. The solution is obtained by help of the apparatus described herein.